Sibling Rivalry
by iloveyooh-x3
Summary: DerekCasey. Derek and Casey start Secretly dating. But what will happen when they go public? R&R. I suck at summarys.
1. 1: Just a Math book?

Sibling Rivalry…

Or not.

Derek looked at Casey, angrily.

"Derek! I know you have my Math book! Now give it back!"

Nora stood in the doorway.

"It's under my bed. Go find it." He smirked

"Ugh! DER-EK!" Casey looked at Nora. "I got it Mom." She sighed.

Nora walked out of the doorway, and swung the door closed behind her.

"Great Acting, Case." Derek smiled, hopping out of the chair in which he had been sitting in.

"You too, Dare." She giggled and slid her arms around his neck, smiling. She kissed him full on the lips, with no intention of stopping. He pulled back and looked at her.

"Derek, do you think of this as incest?" She asked with a scrunched up face of confusion.

"I don't. I mean, tecniclly, we're not brother and sister. Only Step." He smiled.

"Yeah, I guess your right." Casey smiled and kissed him once more, pi8cking up her Algebra book. "Gotta go finish Homework." She sighed.

"Ok." He kissed her on the lips again.

"I love you, Derek Venturi." She smiled.

"And I love you, too, Casey McDonald." He kissed her once more, before she exited the room, grinning.

"Why are you smiling?" She heard a small voice behind her. "You just came out of Derek's room."

"Well, Marti, I finally got my math book back, I can finally get my work done." She giggled and stepped into her room. She sat on the bed and tried to hold back another grin. "Me and Derek, Who would have ever thought we'd be together?


	2. 2: More than siblings

"Casey, would you go to the dance with me?" Sam smiled.

"Um, I would. But I have to work." She said, with a fake sympathetic look.

"Oh. Alright. Maybe I'll stop by?" He asked, sliding an arm around her shoulders.

"Um, the kids will kind of rat me out. And I don't want to lose this. It's the only money I'm making these days." Casey said. Why was she lying to Sam all of the sudden? She knew the answer quickly. She was in love. Not with Sam, but with Derek.

"Oh, okay. I will talk to you later then." He said, walking into his classroom.

Casey continued to walk, seeing as her class was a little ways down. She smiled as she passed Derek, making sure to move her hips a little more than usual. He just smiled as his eyes found his way to where she wanted them to be.

"Hi Derek." She said as she passed. She giggled a bit and walked into her classroom. Derek walked in after her. Every girl's face in the entire room seemed to light up. She heard girls say hi, then giggle towards their friends as he waved a 'was 'up?' towards them. Casey rolled her eyes. Derek was hers. Couldn't they see that? Of course they couldn't. Because Dasey wasn't public just yet.

"Casey, Derek, your wanted in the deans. Again." Mrs. Martin said with a tight smile.

Casey glanced at Derek, then grabbed her books and walked out of the classroom, as Derek followed.

"You know she's going to catch us one of these days." Casey said as she walked past a room.

"Mrs. Martin? I've been leaving her class since I was in 8th grade, she's never caught me." Derek smiled, walking into the room to the right of them. The closet where they put kids who were too sick to me in the nurses office. He sat on the little cot in the corner, after putting his books on the table. Casey made sure the door was locked and put her books down.

"Okay, if you say so." Casey smiled and sat on Derek's lap. Facing him. She kissed him deeply and smiled, pushing him backwards so he was lying on the cot.


	3. 3: Caught?

"Derek, I don't think that we should do this." Casey said, climbing off of him.

"You say that everytime. Case, are we taking our relationship to the next level, or not?" He sighed and looked at her.

"I don't----"

The door swung open and Mrs. Martin stared at the both of them. "Deans. Now"

Casey looked at Derek as her color flushed. "Yes Mam." She said in a hurry, gathering her books and running out of the room. How could have she forgotten that Mrs. Martin had a key to the nurse's extra room? Casey rushed to the deans. She was going to get in so much trouble. She could tell.

"Casey!" Nora said, running over and hugging her. "Lizzie is in the hospital." She sniffled. You could tell she had been crying.

"What happened?!" Casey said, tearing up.

"She collapsed at school. They are trying to figure out what's happening." Nora said, hugging Casey tighter. Derek jogged over.

"Whats going on?" He asked. He looked at Casey, who was sobbing now.

"Liz is in the hospital." Nora said, pulling away from Casey. Derek rubbed Casey back symatheticlly. Casey put her head against his chest and sobbed into him. He hugged her tight and rocked her. Without thinking he kissed her head.

"It'll be ok, Case." Nora said, not noticing.

-----Hospital------

"Lizzie!" Edwin said barging into the room.

"Edwin!" She shouted as she sat up a bit. Edwin hugged her.

"I was so worried." Edwin said into her hair.

"Thanks." She said pulling back and kissing his lips.

Casey's mouth gaped open, along with Derek's.

"What was that?" Casey asked, walking into the room.

"A kiss..." Lizzie said, matter-of-factly.

"But, thats not right." Casey said. "You guys are dating?"

"Yes..." Lizzie said in the same tone.

Derek had the same idea as Casey. Casey ran over, and kissed him full on the lips.


	4. 4: The truth:

Derek and Casey pulled apart and looked at their family.

"Derek, Casey. Are you trying to tell us something?" Nora asked.

"YES!" the both shouted together.

"Well, What makes you think we didn't already know?" George asked, a smile on his lips.

"You knew?!" they said, once again together.

"Yes," Nora started. "When Casey's door opens and Dereks closes, we figure you guys are together. So, we kind of peek in at you." Nora laughed a bit.

"Yeah," George said. "Casey, just a tip, make sure the door is closed all the way when you sneak in." He laughed.

"Sure George." Casey rolled her eyes, but smiled.

"So, You and Ed are an item I see." Derek smirked.

"Derek you say one thing and I w---"

"Ed, I can't say very much since I am in the say position as you." Derek smirked once more.

"But I can say...I SO KNEW YOU AND CASEY BELONGED TOGETHER!" Lizzie said.

"Yea, to tell the truth, All those times I fought with her, she just looked so cute mad at me." Derek smiled at her grabbed her hand. She smiled and looked at him. One, Big, WEIRD, Family. But nonetheless, a very happy one.

**a/n: sorry for the short chapter. i will update soon, with a longer one. . THANKS FOR THE REVIEWS! THEY ARE GREATLY APPRECIATED!**

**--Becca (:**


	5. 5: Public

Derek walked into the Kitchen the next day and smiled. "Hey, Case." He smiled and kissed her lips softly.

"Hey Derek." She smiled, returned the kiss, and then took a bite of her tofu burger. A leftover fromt he night before.

"Casey, do you think we should tell people at school?" Casey nearly choked on her burger.

"Like, go public?!" she asked, after taking a sip of water.

"Yea. I mean, I would think it would be fine. With me being popular and all."

"Yeah, I guess so." Casey gave a tight smile.

"Although I think Mrs. Martin suspects." He laughed a bit.

"I think so." She smiled, remebering the look on Mrs. Martins face.

---at school---

The next day, Derek and Casey sat in Dereks car, hand-in hand. "You ready?" He asked, feeling a bit nervous.

"Yea, I think so." She said.

They got out of the car and walked up to the school doors. Derek took Casey hand as he saw the worried look on her face. "Don't worry." He said, pulling the door open and slinging an arm around her shoulder. She put and arm around his waist and walked through the door, faking a smile.

"Derek, I have to go to my locker, then will you walk me to Chem?" She asked.

"Of course." He said. He winked at her, then started towards his locker. She started towards her own, but was pulled to the side by Emily.

"Um, whats with Derek having his arm around you?" She asked, a confused look on her face.

"Um, I'll explain later." She smiled. Emily looked like she was about to speak, but then Derek came behind Casey and hugged her. "Hey." He smiled, kissing her cheek.

"Ohhhh...Oh!" Emily smiled. "Good luck with that Case." Then she scattered off.

Derek took Casey's hand and smiled. "What was that about?"

"Nothing." She smiled. They walked to her locker and grabbed her book, then Derek did something Casey never expected.

"EVERYONE! LOOK!" He shouted. Everyone looked at them.

And then...He kissed her, and she kissed back, leaning on the wall.

And everyone-------cheered.

**a/n: I am done. . I will write a sequel soon. Ilovemyreviews mucho! thanks! and keep reading my stories!**


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